Summer is set to be a scorcher with warmer than average temperatures predicted for most of the country - yet a mid-season transition may bring relief from the sweltering heat. NIWA has broken down the seasonal climate outlook for the coming summer.
Temperatures
The majority of New Zealand is set to experience above average temperatures during the December 2019 - February 2020 period, with Auckland and the North Island particularly likely to be hit by higher than normal temperatures this summer (50 to 55 percent chance).
Although Otago, Canterbury, Marlborough and Nelson and Bays are also likely to experience sweltering heat this season, the west of the South Island has a 35 percent chance of sticking to its average summer temperatures. The west coast also has the highest probability nationwide of being blighted by below average temperatures (25 percent chance).
NIWA says frequent bouts of warm air masses from Australia crossing the Tasman Sea may contribute to periods of heat, particularly for the eastern South Island and across the North Island. However, a sudden bout of southerlies in the second week of December may bring a spell of cooler conditions for the country.
The sea is also predicted to sit at above average temperatures after increasing during November, meaning balmy beach days are on the horizon.
Rainfall
While this summer is set to have pretty normal rainfall (40 percent chance) nationwide, the west of the South Island has the highest probability (40 percent) of above-average rainfall.
According to NIWA's meteorologist Ben Noll and principal scientist Chris Brandolino, regions of the South Island are likely to be wet during December and the all-important Christmas holiday - so West Coast locals may want to head up north to escape the stormy conditions.
Low pressure over the Tasman Sea may contribute to the West Coast's wet and windy conditions, while Canterbury, Marlborough and Hawke's Bay are likely to enjoy dry and windy heat.
Mid-season transition
A change from westerly winds to north easterlies during the second half of summer may cause a transition in weather for most of the country.
Sunshine and dryness may turn to wet and windy conditions around January and February, meaning a stormier start to summer in the South Island may reverse midway - and vice versa for the North Island.
According to NIWA: "A potential transition from westerly winds in December to northeasterly quarter winds later in the summer could have an impact seasonal rainfall - areas that are wetter (drier) in early summer may be drier (wetter) for the second half of the season."
"It's a summer of two halves," Brandolino says.
